Surgical implant with guiding rail

ABSTRACT

A prosthetic intervertebral spacer is disclosed. The spacer preferably includes a body and an interface extending away from the body for use during implantation of the spacer. Methods of implanting the spacer and tools used during such procedure are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/266,062, filed on Sep. 15, 2016, which is a continuation ofU.S. patent application Ser. No. 14/475,863, filed on Sep. 3, 2014, nowU.S. Pat. No. 9,445,914, which is a continuation of U.S. patentapplication Ser. No. 12/894,796, filed on Sep. 30, 2010, now U.S. Pat.No. 8,858,637, the disclosures of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to spinal implants and methods ofimplanting such implants. More particularly, the present inventionrelates to a spinal implant having a guiding rail for cooperating withan insertion instrument, as well as the methods associated withimplanting that implant.

Back pain can be caused by many different things, including any one ofseveral problems that affect the intervertebral discs of the spine.These disc problems include, for instance, degeneration, bulging,herniation, thinning of a disc, and abnormal movement, and the pain thatis experienced is generally attributable to friction or pressure thatinevitably occurs when one adjacent vertebra exerts uneven pressure orwhen both adjacent vertebrae exert such pressure on the disc.Oftentimes, disc problems lead to the vertebrae impinging on one of thevery many nerves located in the spinal column.

One surgical method commonly utilized to correct such disc problems is afusion procedure where a surgeon fuses together adjacent vertebrae insingle or multiple levels. Different methods (as well as apparatus foruse in those methods) for such surgery have been developed forperformance on cervical, thoracic, or lumbar vertebral bodies. Thesefusion procedures will be referred to herein as interbody fusion or“IF.” Traditional IF techniques generally involve removing at least aportion of the troublesome disc from the patient, inserting a spinalimplant device into the space to hold the graft material in place and tosupport the vertebrae while solid bone mass forms therebetween, andadding bone graft material into the interbody space between thevertebrae that flank the disc. Oftentimes, the steps of inserting animplant and bone graft material involve first packing the implant withthe bone graft material, and thereafter implanting that construct.

While IF is a long-established technique for correcting theaforementioned disc problems, it is one that is constantly updated. Forinstance, different implants have been created to suit specific needs,and methods involving the insertion of such implants and the preparationof the vertebrae to receive same are constantly evolving. One majorissue that has existed and will continue to exist is the fact thatvisibility to the surgical site is often hindered by the patientanatomy. For instance, in the cervical section of the spine, thevertebral bodies are rather small and surrounding patient anatomy, suchas the esophagus and other body parts, makes access to and visibility ofthe surgical site rather difficult. This often hinders the surgeon inproperly positioning an implant with respect to the vertebrae.Furthermore, in many IF procedures, the required manipulation of thepatient anatomy, distraction of the vertebral bodies, and preparation ofthe vertebral bodies often results in significant scar tissue beingformed in the patient. This can be detrimental when performing anysubsequently required spinal procedures.

Thus, there exists a need for a spinal implant and method of using theimplant that improves upon these shortcomings.

BRIEF SUMMARY OF THE INVENTION

A first aspect of the present invention is a prosthetic intervertebralspacer. In accordance with one embodiment of this first aspect, thespacer includes a body having a front end, a rear end, an anterior side,a posterior side, a top surface, a bottom surface, and an arcuateinterface extending away from the body and being connected to the rearend and the posterior side of the body.

In accordance with other embodiments of the first aspect, the interfacemay include a rail including a neck portion connected to the body and alip portion connected to the neck portion. The lip portion may be widerthan the neck portion in the direction extending between the top andbottom surfaces. The neck and lip portions of the interface may form a Tshape. Additionally, a notch may be included in the interface, therebyseparating the rail into a first rail segment and a second rail segment.The first rail segment may be disposed on the rear end of the spacer,and the second rail segment may be disposed on the posterior side of thespacer. The notch may extend in a direction substantially parallel to alongitudinal axis of the spacer.

In accordance with still other embodiments of the first aspect, the rearend of the spacer may be curved, so that in certain cases, the curves ofthe rear end and the arcuate interface may lie on concentric circles. Inother embodiments, the front end may be curved, and may include asteering element configured to mate with an adjacent vertebral body tocause rotation of the spacer during insertion. In certain embodiments,the steering element may be a fin or a crease, and may be disposed at anangle with respect to a longitudinal axis of the spacer. Still further,the spacer may include at least one aperture extending between the upperand lower surfaces. The aperture may allow for bone growth inducingsubstances to be placed therein.

A second aspect of the present invention is another prostheticintervertebral spacer. In accordance with one embodiment of the secondaspect, the spacer includes a body defined by an outer wall having aconvexly curved front end, a convexly curved rear end, a convex anteriorside, a concave posterior side, a top surface, and a bottom surface. Thespacer further includes an arcuate interface protruding from the outerwall and being connected to the rear end and the posterior side of thebody, where the interface is a rail including a neck portion connectedto the body and a lip portion connected to the neck portion. The lipportion has a first dimension greater than a second dimension of theneck portion, and the outer wall has a third dimension greater than thefirst dimension, the first and third dimensions extending between thetop and bottom surfaces.

In accordance with other embodiments of this second aspect, the rail mayfurther include a notch separating the rail into first and second railsegments. The notch may extend in a direction substantially parallel tothe longitudinal axis of the spacer. The first rail segment may bedisposed on the rear end of the spacer, and the second rail segment maybe disposed on the posterior side of the spacer. Further, the neckportion and lip portion of the interface may form a T shape.

In other embodiments according to the second aspect, the front end mayinclude a steering element configured to mate with an adjacent vertebralbody to cause rotation of the spacer. The steering element may be a finor a crease. Additionally, the steering element may be disposed at anangle with respect to the longitudinal axis of the spacer. Finally, thespacer may include at least one aperture extending between the upper andlower surfaces. The aperture may allow for bone growth inducingsubstances to be placed therein.

A third aspect of the present invention is another prostheticintervertebral spacer. This spacer according to the third aspect mayinclude a body having a front end, a rear end, an anterior side, aposterior side, and a longitudinal axis. The front end preferably mateswith the anterior side at a transition portion that is curved, thetransition portion being configured to interact with an annulus fibrosisof an intervertebral disc to cause rotation in the spacer duringinsertion of the spacer. The spacer may further include an arcuateinterface extending away from the body and being connected to the rearend and the posterior side of the body. In certain embodiments, theinterface may be a rail including a neck portion connected to the bodyand a lip portion connected to the neck portion, the lip portion beingwider than the neck portion in the direction extending between the topand bottom surfaces.

A fourth aspect of the present invention is a surgical tool forinserting and positioning a prosthetic intervertebral spacer in theintervertebral disc space between two adjacent vertebrae. In accordancewith one embodiment of the fourth aspect, the tool includes a graspingportion including first and second arms having proximal and distal ends,the distal ends being separated by a first dimensions; a sleeve havingan inner surface, the sleeve being slidably disposed about the graspingportion, at least the portion of the inner surface having an innerdimension less than the first dimension; a handle portion connected tothe proximal ends in the first and second arms, the handle portionhaving a rod actuator and a sleeve actuator, the sleeve actuatorconnected to the sleeve to slide the sleeve with respect to the firstand second arms; and a rod having a first end disposed adjacent thedistal ends of the first and second arms and a second end, the rodactuator connected to the second end to slide the rod with respect withto the grasping portion.

In accordance with other embodiments of the fourth aspect of the presentinvention, the first and second arms may be flexibly connected to thehandle portion such that the distal ends of the first and second armscan move toward and away from another. Further, the first and secondarms may also include proximal ends separate by a second distance lessthan the first distance. Each of the distal ends of the first and secondarms may include a projection facing toward the opposite arm forengagement to an interface of the spacer. The distal ends of the firstand second arms may be curved to mate with the inner face of the spacer.

In still further embodiments, the inner dimension may be greater thanthe second distance. The handle portion may include a grip and a shaftportion, the shaft portion having a proximal end connected to the gripand a distal end connected to the grasping portion. Likewise, the sleeveactuator may include a rotatable knob disposed on the handle portion.Still further, the rod actuator may include a slidable switch disposedon the handle portion and a screw for locking the slidable switch withrespect to the handle portion.

A fifth aspect of the present invention is a method of using a surgicaltool for inserting and positioning a prosthetic intervertebral spacer inthe intervertebral disc space between two adjacent vertebrae. Inaccordance with one embodiment of this aspect, the method may includethe steps of providing a surgical tool including a grasping portionhaving first and second arms having proximal and distal ends, the distalends being separated by a first dimension; a sleeve having an innersurface, the sleeve being slidably disposed about the grasping portion,at least a portion of the inner surface having an inner dimension lessthan the first dimension; a handle portion connected to the proximalends of the first and second arms, the handle portion having a rodactuator and a sleeve actuator, the sleeve actuator connected to thesleeve to slide the sleeve with respect to the first and second arms;and a rod having a first end disposed adjacent the distal ends of thefirst and second arms and a second end, the rod actuator connected tothe second end to slide the rod with respect to the grasping portion.The method may also include the steps of positioning distal ends of thefirst and second arms adjacent in interface of an intervertebral spacer,moving the sleeve such that the portion of the inner surface to thesleeve having the inner dimension overlaps the distal ends of the firstand second arms, thereby engaging the tool to the interface of thespacer, and engaging the first end of the rod to a notch in the spacer.

In accordance with other embodiments of the fifth aspect, the method mayfurther include the steps of inserting the spacer into theintervertebral disc space, disengaging the first end of the rod from thenotch, and/or further inserting the spacer into the intervertebral spacewhen the rod is disengaged from the notch. The tool may be configured toslide along the interface of the spacer when engaged with the spacer,where the step of further inserting the spacer includes sliding the toolalong the interface of the spacer while the spacer rotates in theintervertebral disc space. Relative rotation of the spacer may beprevented when the rod is engaged to the notch and permitted when therod is disengaged from the notch. The step of disengaging may beconducted when the spacer contacts a portion of an annulus fibrosis inthe anterior portion of the intervertebral disc space.

In further embodiments, the method of the fifth aspect may furtherinclude the step of forming a hole through only a portion of the annulusfibrosis while leaving the remainder of the annulus fibrosis in tact,where the step of inserting includes inserting the spacer through thehole. The step of moving the sleeve may include actuating the sleeveactuator. The method may further include the step of tightening the gripof the tool on the spacer by rotating a rotatable knob of the sleeveactuator. The step of engaging the first end of the rod may includeactuating a rod actuator. The step of actuating may include sliding aslidable switch through the road actuator with respect to the handleportion and locking the slidable switch to the handle portion bytightening the screw of the rod actuator. The method may further includethe step of disengaging the first end of the rod from the notch byloosening the screw and sliding the slidable switch with respect to thehandle portion. The first and second arms of the tool may be flexiblyconnected to the handle portion and the step of moving the sleeve maycause the distal ends of the first and second arms to move toward oneanother. In still further embodiments, each of the distal ends of thefirst and second arms may include a projection facing toward theopposite arm for engagement to an interface of the spacer, and the stepof moving the sleeve may cause the distal ends of the first and secondarms to engage the projections to mating channels in the interface ofthe spacer. Additionally, the handle portion may include a grip and ashaft portion, the shaft portion having a proximal end connected to thegrip and a distal end connected to the grasping portion.

A sixth aspect of the present invention is another method of using asurgical tool for inserting and positioning a prosthetic intervertebralspacer in the intervertebral disc space between two adjacent vertebrae.The method according to the sixth aspect may include the steps ofpositioning distal ends of first and second arms with a surgical tooladjacent an interface of intervertebral spacer, the distal ends beingseparated by a first dimension, moving a sleeve of the tool such that aportion of an inner surface of the sleeve having an inner dimension lessthan the first dimension overlapped the distal ends of the first andsecond arms, thereby engaging the tool to the interface of the spacer,and engaging a rod of the tool to a notch in the spacer.

In accordance with embodiments of the sixth aspect, the method mayfurther include the steps of inserting the spacer into theintervertebral space, disengaging the rod from the notch, and/or furtherinserting the spacer into the intervertebral space when the rod isdisengaged from the notch. In further embodiments, the tool may beconfigured to slide along the interface of the spacer when engaged withthe spacer, with the step of further inserting the spacer includessliding the tool along the interface of the spacer while the spacerrotates in the intervertebral disc space. Relative rotation between thespacer and the tool may be prevented when the rod is engaged to thenotch and permitted when the rod is disengaged from the notch. The stepof disengaging may be conducted when the spacer contacts the annulusfibrosis in the anterior portion of the intervertebral disc space.

Further, the method of this sixth aspect, may further comprise the stepof forming a hole through only a portion of the annulus fibrosis whileleaving the remainder of the annulus fibrosis in tact, where the step ofinserting includes inserting the spacer through the hole. The step ofmoving the sleeve may include actuating the sleeve actuator of the toolthereby tightening the grip of the tool on the spacer by rotating arotatable knob of the sleeve aperture. The step of engaging the rod mayinclude actuating the rod actuator of the tool, including sliding theslidable switch of the rod actuator with respect to the handle portionand locking the slidable switch to the handle portion by tightening ascrew of the rod actuator. The method may further comprise the step ofdisengaging the first end of the rod from the notch by loosening thescrew and sliding the slidable switch with respect to the handleportion. The first and second arms of the tool may be flexibly connectedto a handle portion of the tool, and the step of moving a sleeve maycause the distal ends of the first and second knobs to move towards oneanother. Each of the distal ends of the first and second arms mayinclude a projection facing toward the opposite arm for engagement to aninterface of the spacer, and the step of moving the sleeve may cause thedistal ends of the first and second arms to engage the projections tomating channels in the interface of the spacer.

A seventh aspect of the present invention is a method of inserting andpositioning a prosthetic intervertebral spacer in an intervertebral discspace between two adjacent vertebrae. In accordance with one embodimentof the seventh aspect, the method may include the steps of providing aspacer including a body having a front end, a rear end, a longitudinalaxis, and an interface extending away from the body and being connectedto the rear end of the body, engaging a tool to the interface; insertingthe spacer at least partially into the intervertebral disc space bymoving the tool along an insertion direction; and allowing the spacer torotate with respect to the insertion direction within in theintervertebral disc space while continuing to move the tool along theinsertion direction.

In accordance with certain embodiments of the seventh aspect, the toolmay maintain its engagement to the interface during the steps ofinserting and allowing. The step of allowing the spacer to rotate mayinclude allowing the front end to interact with an annulus fibrosis ofan intervertebral disc to cause rotation in the spacer with respect tothe insertion direction. The method may further include the step offorming a hole through only a portion of the annulus fibrosis whileleaving the remainder of the annulus fibrosis in tact, where the step ofinserting includes inserting the spacer through the hole. The spacer maybe inserted such that the spacer is positioned in an anterior aspect ofthe intervertebral disc space. The spacer may be inserted to a finalposition where the longitudinal axis of the spacer is perpendicular tothe insertion direction. The longitudinal axis of the spacer may besubstantially parallel to a medial lateral axis of the intervertebraldisc space. The spacer may be inserted such that the longitudinal axisof the spacer is rotated approximately 80 degrees with respect to theinsertion direction. The allowing step may include allowing the tool toslide along the interface during rotation of the spacer. The insertiondirection may be substantially parallel to a posterior-anterior axis ofthe intervertebral disc space. The interface of the spacer may include anotch and the tool may include a rod engageable to the notch, where themethod further includes the step of engaging the rod to the notch toprevent relative rotation between the spacer and the tool and the stepof disengaging the rod from the notch to allow relative rotation betweenthe spacer and the tool. The allowing step may take place after the rodis disengaged from the notch. The spacer may at least be partiallyinserted with the rod engaged to the notch and at least partiallyinserted with the rod from the notch. The body may further include a topsurface, a bottom surface, and at least one aperture extending betweenthe top and bottom surfaces, where the method further includes the stepof packing bone graft material into the at least one aperture. Thespacer may further include a front end having frictional properties thatare greater than frictional properties of a rear end in the spacer toaid in the rotation of the spacer within the intervertebral space. Thestep of allowing the spacer to rotate further may include allowing asteering element disposed on the front end of the spacer to mate withone of the two adjacent vertebral bodies to cause rotation of the spacerwith respect to the insertion direction. The steering element may bedisposed at an angle with respect to the longitudinal axis. The steeringelement may be a fin or crease.

An eighth aspect of the present invention is another method of insertingand positioning a prosthetic intervertebral spacer in an intervertebraldisc space between two adjacent vertebrae. In accordance with oneembodiment of the eighth aspect, the method may include the steps ofproviding a spacer including a body having a front end, a rear end, alongitudinal axis, and an interface extending away from the body andbeing connected to the rear end of the body, the interface including anotch; engaging a tool to be interface, the tool including a rod;engaging the rod to the notch to prevent relative rotation between thespacer and the tool; inserting the spacer at least partially into theintervertebral disc space by moving the tool along an insertiondirection; disengaging the rod from the notch; inserting the spacerfurther into the intervertebral disc space after the disengaging step bymoving the tool substantially along the insertion direction; andallowing the spacer to rotate with respect to the insertion directionwithin the intervertebral disc space when the rod is disengaged from thenotch while continuing to move the tool along the insertion direction.

In accordance with certain embodiments of the eighth aspect, the methodmay further include the step of forming a hole through only a portion ofan annulus fibrosis while leaving the remainder of the annulus fibrosisintact, where the step of inserting includes inserting the spacerthrough the hole. The step of allowing the spacer to rotate may includeallowing the front end to interact with an annulus fibrosis of anintervertebral disc to cause rotation to the spacer with respect to theinsertion direction. The tool may maintain its engagement to theinterface during the steps of inserting and allowing. The spacer may beinserted such that the spacer's position in an anterior aspect of theintervertebral disc space. The spacer may be inserted to a finalposition where the longitudinal axis of the spacer is perpendicular tothe insertion direction. The longitudinal axis of the spacer may besubstantially parallel to a medial-lateral axis of the intervertebraldisc space. The spacer may be inserted such that the longitudinal axisof the spacer is rotated approximately 80 degrees with respect to theinsertion direction. The allowing step may include allowing the tool toslide along the interface during rotation of the spacer. The front endof the spacer may include a steering element, and the step of allowingthe spacer to rotate further may include allowing the steering elementto mate with one of the adjacent vertebral bodies to cause a rotation ofthe spacer with respect to the insertion direction. The steering elementmay be disposed at an angle with respect to the longitudinal axis. Thesteering element may be a fin or crease. The insertion direction may besubstantially parallel to a posterior that is entered axially in avertebral disc space.

Further, the body may include a top surface, a bottom surface, and atleast one aperture extending between the top and bottom surfaces, wherethe method further includes the step of packing bone graft material intothe at least one aperture. The spacer may further include a front endhaving frictional properties that are greater than frictional propertiesof a rear end of the spacer to aid in the rotation of the spacer withinthe intervertebral disc space. The first step of inserting may includeapplying a force to the spacer along a first axis substantially parallelto the longitudinal axis of the spacer, and the second step of insertingmay include applying a force to the spacer along a second axis formingan angle with the axis of great than zero degrees.

A ninth aspect of the present invention is another method of insertingand positioning a prosthetic intervertebral spacer in an intervertebraldisc space between two adjacent vertebrae. In accordance with oneembodiment of the ninth aspect, the method may include the steps ofproviding a spacer including a body having a front end, a rear end, alongitudinal axis, and an interface extending away from the body andbeing connected to the rear end of the body; applying a force to a toolengaged to the interface to move the spacer in the intervertebral discspace, the force being directed along an insertion direction; andallowing the front end to interact with an annulus fibrosis of anintervertebral disc to cause rotation in the spacer with respect to theinsertion direction while continuing to move the tool along theinsertion direction.

In other embodiments of the ninth aspect, the method may further includethe step of forming a hole through only a portion of the annulusfibrosis while leaving the remainder of the annulus fibrosis intact, andthe step of inserting the spacer through the hole. The engaging betweenthe tool and the interface may be maintained during the steps ofapplying and allowing. The allowing step may include allowing the toolto slide along the interface during rotation of the spacer. Theinterface of the spacer may include a notch and the tool may include arod engaged to the notch, where the method further includes the step ofengaging the rod to the notch to prevent relative rotation between thespacer and the tool and the step of disengaging the rod from the notchto allow relative rotation between the spacer and the tool. The allowingstep may take place after the rod is disengaged from the notch. Thespacer may be at least partially inserted with the rod engaged to thenotch and at least partially inserted with the rod disengaged from thenotch. The step of allowing may include allowing a steering elementdisposed on the front end of the spacer to meet with an adjacentvertebral body to cause rotation of the spacer with respect to theinsertion direction. The steering element may be disposed at an anglewith respect to the longitudinal axis. The steering element may be a finor a crease. The step of applying may include the insertion directionbeing substantially parallel to the longitudinal axis of the spacer andthe method may further include the step of applying a second force tothe spacer along the second axis forming an angle with the longitudinalaxis of greater than zero degrees.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the subject matter of the presentinvention and the various advantages thereof can be realized byreference to the following detailed description in which reference ismade to the accompanying drawings in which:

FIG. 1 is a front perspective view of a prosthetic intervertebral spacerin accordance with one embodiment of the present invention.

FIG. 2 is a top perspective view of the spacer shown in FIG. 1.

FIG. 3 is a top view of the spacer shown in FIG. 1, the bottom viewbeing a mirror image thereof.

FIG. 4 is a side view of the spacer shown in FIG. 1.

FIG. 5 is a cross-sectional view of a modified version of the spacershown in FIG. 1, the section being taken through the modified version ina similar fashion to line X-X of FIG. 1.

FIG. 6 is a perspective view of a surgical tool for use in inserting andpositioning a prosthetic intervertebral spacer in accordance with oneembodiment of the present invention.

FIG. 7 is an exploded view of the insertion tool shown in FIG. 6.

FIG. 8 is an enlarged exploded view of a portion of the view of FIG. 7.

FIG. 9 is in illustration depicting an initial connection between thespacer shown in FIG. 1 and the insertion tool shown in FIG. 6.

FIG. 10 is an illustration depicting the spacer and insertion toolconstruct shown in FIG. 9 with the insertion tool in a locked position.

FIG. 11 is an illustration depicting the spacer and insertion toolconstruct shown in FIG. 9 with the spacer rotated with respect to theinsertion tool.

FIG. 12 is an illustration of the spacer and insertion tool constructshown in FIG. 9 with the spacer fully rotated with respect to theinsertion tool.

FIG. 13 is an illustration depicting the spacer and insertion toolconstruct shown in FIG. 9 with the spacer released from the insertiontool.

FIG. 14 is an illustration depicting the spacer and insertion toolconstruct shown in FIG. 9 in relation to an intervertebral space.

FIG. 15 is an illustration depicting the spacer and insertion toolconstruct shown in FIG. 9 in relation to the intervertebral space, withthe spacer in a fully inserted position.

FIGS. 16a-16g are illustrations depicting various stages of insertion ofthe spacer shown in FIG. 1 in relation to the insertion tool shown inFIG. 6 and a vertebral body.

FIG. 17 is a perspective view of a prosthetic intervertebral spacer inaccordance with another embodiment of the present invention.

DETAILED DESCRIPTION

In describing the preferred embodiments of the subject illustrated andto be described with respect to the drawings, specific terminology willbe used for the sake of clarity. However, the invention is not intendedto be limited to any specific terms used herein, and it is to beunderstood that each specific term includes all technical equivalentsthat operate in a similar manner to accomplish similar purpose.

As used herein, when referring to bones or other parts of the body, theterm “proximal” means closer to the heart and the term “distal” meansmore distant from the heart. The term “inferior” means toward the feetand the term “superior” means towards the head. The term “anterior”means towards the front part of the body or the face and the term“posterior” means towards the back of the body. The term “medial” meanstoward the midline of the body and the term “lateral” means away fromthe midline of the body.

Referring to FIGS. 1-4, there is shown a prosthetic intervertebralspacer 10 in accordance with one embodiment of the present invention. Asshown, spacer 10 includes a body 12, which in turn includes a front end14, a rear end 16, an anterior side 18, a posterior side 20, a topsurface 22, and a bottom surface 24. Spacer 10 further includes aninterface 26, including a neck portion 28, a lip portion 30, and a notch32. Notch 32 separates interface 26 into first and second segments 26 aand 26 b (best shown in FIGS. 2 and 3), respectively. In the embodimentshown in FIGS. 1-4, interface 26 is arcuate and can best be described asa rail. However, in other embodiments, interface 26 can vary in shape,size, and configuration, with the only limitation being its cooperationwith an insertion tool, such as the one discussed more fully below.Likewise, in the embodiments shown in FIGS. 1-4, notch 32 is shown asextending in a direction substantially parallel to a longitudinal axisof spacer 10, and neck portion 28 and lip portion 30 are shown asforming a T-shape. Again, these elements can vary in other embodiments.

Spacer 10 is preferably constructed of a polymeric material, such aspolyetheretherketone (“Peek”). However, spacer 10 may be constructed ofpractically any materials suitable for implantation in the body of ahuman. Front end 14 and rear end 16 are shown as being curved, where thecurves of the rear end and arcuate interface 26 lie in concentriccircles. Again, in other embodiments, this configuration may vary. Forinstance, it is contemplated to provide a substantially square orrectangular shaped spacer 10. In the embodiment shown in FIGS. 1-4,front end 14 defines a tapered nose for spacer 10. However, in otherembodiments, front end 14 may (additional to or in lieu of the taperednose structure) include a steering element configured to mate with atleast one of the adjacent vertebral bodies spacer 10 is designed to beplaced between in order to cause rotation of spacer 10 during insertion.Such a steering element may include a fin or crease, and may be disposedat an angle with respect to longitudinal axis of spacer 10. One examplespacer 110 of this type is depicted in FIG. 17, in which a steeringelement 112 takes the form of a crease. Of course, in other embodimentsemploying such a steering element, other designs may be employed.

In the embodiment shown, top and bottom surfaces 22 and 24 each includea plurality of bone-engaging features in the form of teeth 34. Otherfeatures may be employed for aiding in the fixation of spacer 10 to theadjacent vertebrae. Spacer 10 also includes apertures 36 a and 36 bformed through top and bottom surfaces 22 and 24. Apertures 36 a and 36b are separated by a strut 38, which is recessed with respect to bothtop and bottom surfaces 22 and 24. In other embodiments, strut 38 may beformed flush with top and bottom surfaces 22 and 24, or only recessedwith respect to one or the other. Apertures 36 a and 36 b are preferablydesigned to receive bone growth material, as will be discussed morefully below. Apertures 36 a and 36 b also exhibit an oblong shape inorder to avoid sharp corners that generally create engineering stressesand may cause harm to the interior patient anatomy. Spacer 10 furtherincludes lateral fenestrations 40 a and 40 b, which are preferablydesigned for allowing fusion that develops between the upper and lowervertebrae (through the spacer) to spread laterally as well, and aplurality of vertical markers 42 a and 42 b, which are preferablyconstructed of tantalum and press fitted into spacer 10. Markers 42 aand 42 b make the visual identification of spacer 10 easier through atraditional X-ray technique.

Spacer 10 shown in FIGS. 1-4 preferably includes a length dimension fromfront end 14 to rear end 16 that is preferably within the range of 15 mmto 40 mm, and more preferably between 26 mm and 31 mm, as well as alength dimension from front end 14 to the end of interface 26 that ispreferably within the range of 17 mm to 42 mm, and more preferablybetween 28 mm and 32 mm. A width dimension from anterior side 18 toposterior side 20 of spacer 10 shown in FIGS. 1-4 is preferably in therange of 8 mm to 16 mm, and more preferably approximately 12 mm spacer10 shown in FIGS. 1-4 also preferably includes a height dimension fromtop surface 22 to bottom surface 24 within the range of 6 mm to 15 mm ofcourse, in other embodiments, spacer 10 may be of any size. Forinstance, spacers 10 designed for use in the cervical area of the spinemay be smaller than spacers 10 designed for use in the thoracic orlumber spine.

Although shown in FIGS. 1-4 as having top and bottom surfaces 22 and 24situated in a parallel fashion with respect to each other, FIG. 5depicts a version of spacer 10 exhibiting top and bottom surfaces 22 and24 that taper from anterior side 18 to posterior side 20. This taperedconstruction preferably aids in restoring the natural lordotic angle ofthe adjacent vertebrae. The angle of each taper is preferably within therange of zero to ten degrees with respect to the midplane of spacer 10to comport with the natural lordotic angle, but may be any anglesuitable for use in the spine. The particular patient anatomy willgenerally determine whether a spacer like that shown in FIGS. 1-4 or inFIG. 5 will be required. However, a surgeon may employ one design or theother for other reasons.

FIGS. 6-9 depict an insertion tool 50 for use in inserting andpositioning a prosthetic intervertebral spacer, for instance,above-described spacer 10, in the intervertebral disc space between twoadjacent vertebra. As is more clearly shown in the exploded view ofFIGS. 7 and 8, insertion tool 50 includes a grasping portion 52 havingfirst and second arms 54 a and 54 b that are preferably capable ofmoving with respect to one another. In the particular embodiment shown,arms 54 a and 54 b act as spring clips having proximal ends attached toother portions of grasping portion 52 and distal ends between which thedimension can be varied. In other embodiments, arms 54 a and 54 b may bemovable in other fashions, such as rotatable or the like. Tool 50further includes a sleeve 56 having an inner surface 57 that is slidablydisposed about grasping portion 52. A portion of inner surface 57 ofsleeve 56 includes opposing surfaces that are preferably spaced apart bya dimension that is less than a resting dimension between the outerportions of arms 54 a and 54 b. This allows for the distance betweenarms 54 a and 54 b to be reduced upon sliding of the sleeve distally.This preferably allows for arms 54 a and 54 b to be in an initialposition, such as separated by the resting dimension, where they areable to receive spacer 10, and where sliding of sleeve 56 causes arms 54a and 54 b to affix to interface 26. In this regard, arms 54 a and 54 beach preferably include projections 58 a and 58 b, respectively, forpositioning adjacent to the shoulder formed between neck portion 28 andlip portion 30 of interface 26. Moreover, arms 54 a and 54 b andprojections 58 a and 58 b are preferably curved to properly mate withthe curvature of interface 26 and therefore to allow rotation of spacer10 with respect to tool 50. The rotational relationship between spacer10 and tool 50 will be discussed more fully below.

As best shown in FIG. 6, tool 50 further includes a handle portion 60connected to grasping portion 52. Handle portion 60 preferably furtherincludes a sleeve actuator 62 for causing sliding movement of sleeve 56.In the embodiment shown, sleeve actuator 62 includes a rotatable knob,the rotation of which causes the sliding of sleeve 56. Handle portion 60also preferably includes a rod actuator 63 for causing movement of a rod64 (best shown in FIGS. 7 and 8) that acts as a rotational lock forspacer 10. In the embodiment shown, rod actuator 63 takes the form of aswitch, the sliding of which causes movement of rod 64. Handle portion60 also preferably includes a grip 66 that may be ergonomically shapedand formed with a material suitable for grasping by a surgeon.

FIGS. 9-13 depict the mating relationship between spacer 10 andinsertion tool 50. With reference to FIG. 9, the initial connectionbetween spacer 10 and tool 50 is depicted. As noted above, arms 54 a and54 b are preferably in an initial state suitable for receiving interface26 of spacer 10. With reference to FIG. 10, the inserter is shown withsleeve 56 slid over arms 54 a and 54 b to affix spacer 10 to tool 50. Inaddition, rod 64 is shown deployed into notch 32. Thus, spacer 10 canneither be removed from nor rotated with respect to tool 50. FIG. 11depicts spacer 10 rotated with respect to tool 50. Essentially, in FIG.11, rod 64 has been disengaged from notch 32 through actuation of rodactuator 64. The arcuate nature of interface 26 and arms 54 a and 54 ballows for the rotation between the components. FIG. 12 depicts spacer10 rotated at a maximum amount with respect to tool 50. This amount isapproximately 80 degrees, but may be greater in other embodiments,including approximately 90 degrees. Where FIGS. 9 and 10 depicted themajority of tool 50 being connected with first segment 26 a of interface26, FIG. 12 depicts the majority of tool 50 being connected with secondsegments 26 b due to the rotation of spacer 10 with respect to tool 50.Finally, FIG. 13 depicts spacer 10 having been released from tool 50upon sliding of sleeve 56 in the opposite direction from which it isshown in FIGS. 10-12.

FIGS. 14 and 15 depict the spacer 10 and tool 50 construct discussedabove in relation to two adjacent vertebral bodies in the spine of ahuman being. Although FIG. 14 depicts spacer 10 being inserted from aposterior aspect of the spine, spacer 10 may be inserted from anyaspect. For instance, in other embodiments, spacer 10 is inserted froman anterior aspect of the spine. Likewise, although shown in FIG. 15 ina final position located in an anterior portion of the intervertebraldisc space, spacer 10 may ultimately be disposed in many different areasof that intervertebral disc space. For example, spacer 10 may ultimatelybe implanted so as to be located in a posterior portion of theintervertebral space.

FIGS. 16a-16g depict in more detail one embodiment method of insertingand positioning spacer 10 in the intervertebral disc space between twoadjacent vertebra with the use of tool 50. Prior to conducting themethod shown in those figures, a surgeon preferably forms a hole throughthe annulus fibrosis of an intervertebral disc space, leaving a largeamount of that anatomical feature untouched. The surgeon may then remove(through the formed hole or otherwise) certain material from the spacein order to allow for spacer 10 to be inserted therein. Thereafter, asshown in FIG. 16a , the locked spacer 10 and tool 50 construct shown inFIG. 10 is inserted through the hole formed through the annulusfibrosis. Again, while this is shown in FIG. 16a as having occurred froma posterior lateral aspect, other entry aspects may be utilized ininserting spacer 10. Upon contact of spacer 10 with a remaining portionof the annulus fibrosis (see FIG. 16b ) rod actuator 63 is actuated towithdraw the rotational lock provided by rod 64 being disposed withinnotch 32. Spacer 10 is then allowed to rotate with respect to tool 50during further insertion of the construct within the space, as front end14 engages the remaining portion of the annulus fibrosis. FIGS. 16c-16edepict subsequent and sequential steps in this insertion process. FIG.16f depicts spacer 10 fully rotated with respect to insertion tool 50and disposed in an anterior portion of the disc space where, in thisembodiment, it shall remain. FIG. 16g depicts tool 50 being removed fromspacer 10. This is due to operation of sleeve actuator 62 to slidesleeve 56 with respect to grasping portion 52. Spacer 10 is now in itsfinal position and tool 50 can be removed from the space.

The methods of inserting spacer 10 may further include the steps ofpacking apertures 36 a and 36 b with bone growth inducing substances,such as bone morphogenetic proteins or natural bone materials. Inembodiments in which spacer 10 includes a steering element, the rotationbetween spacer 10 and tool 50 may occur prior to engagement of spacer 10with the remaining portion of the annulus fibrosis. In addition, it isto be understood that the tapered nose of front end 14 of spacer 10preferably aids in the initial insertion of the spacer within theintervertebral disc space, as well as the cooperation of the spacer withthe remaining portion of the annulus fibrosis.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. (canceled)
 2. A prosthetic intervertebral spacer comprising a bodyhaving a front end, a rear end, anterior and posterior sides eachextending between the front and rear ends, and top and bottom surfaceseach connecting the anterior and posterior sides and extending betweenthe front and rear ends, at least one of the top and bottom surfacesincluding a plurality of teeth, each of the plurality of teeth having aflat uppermost surface and a base, the plurality of teeth touching oneanother at their respective bases.
 3. The spacer of claim 2, wherein theanterior side of the body defines fenestrations for allowing bonegrowth.
 4. The spacer of claim 2, wherein the plurality of teeth contactone another to completely cover a continuous portion of the at least oneof the top and bottom surfaces.
 5. The spacer of claim 2, wherein theother of the top and bottom surfaces includes a plurality of teeth eachhaving a flat uppermost surface and a base and touching one another attheir respective bases.
 6. The spacer of claim 2, further comprising aplurality of radiographic markers disposed within the body.
 7. Thespacer of claim 6, wherein the plurality of radiographic markers areeach comprised of tantalum.
 8. The spacer of claim 2, further comprisingan interface extending away from the body, the interface extending alongan arcuate path and being connected to the body along an arcuateperiphery thereof from a rear-facing surface to the a posterior-facingsurface of the body, wherein the interface is a rail including a neckportion connected to the body and a lip portion connected to the neckportion, the lip portion being wider than the neck portion in adirection extending between the top and bottom surfaces.
 9. The spacerof claim 8, wherein the neck portion separates the lip portion from thebody at a first rail segment.
 10. The spacer of claim 9, furtherincluding a second rail segment separated from the first rail segment bya notch.
 11. The spacer of claim 10, wherein the notch extends in adirection substantially parallel to a longitudinal axis of the spacer.12. The spacer of claim 10, wherein the first rail segment is disposedon the rear end of the spacer, and the second rail segment is disposedon the posterior side of the spacer.
 13. The spacer of claim 8, whereinthe neck portion and the lip portion form a T-shape.
 14. The spacer ofclaim 8, wherein the rear end is curved, and curves of the rear end andat least a portion of the arcuate path lie on concentric circles. 15.The spacer of claim 2, wherein the front end includes a steering elementconfigured to mate with an adjacent vertebral body to cause rotation ofthe spacer.
 16. The spacer of claim 15, wherein the steering element isa fin or a crease.
 17. The spacer of claim 2, wherein at least oneaperture extends between the top and bottom surfaces.
 18. A prostheticintervertebral spacer comprising a body having a front end, a rear end,anterior and posterior sides each extending between the front and rearends, and top and bottom surfaces each connecting the anterior andposterior sides and extending between the front and rear ends, at leastone of the top and bottom surfaces including a plurality of teeth, eachof the plurality of teeth having a flat uppermost surface and a base,the plurality of teeth touching one another at their respective bases.19. A prosthetic intervertebral spacer comprising: a body defined by anouter wall having a convexly curved and tapered front end, a convexlycurved rear end, a convex anterior side and a concave posterior sideeach extending between the front and rear ends, and top and bottomsurfaces each connecting the anterior and posterior sides and extendingbetween the front and rear ends, the anterior side of the body definingfenestrations for allowing bone growth, at least one of the top andbottom surfaces including a plurality of teeth, each of the plurality ofteeth having a flat uppermost surface and a base, the plurality of teethtouching one another at their respective bases; an interface protrudingfrom the outer wall, the interface extending along an arcuate path andbeing connected to the body along an arcuate periphery thereof from arear-facing surface to a posterior-facing surface of the body; and aplurality of radiographic markers disposed within the body.
 20. Thespacer of claim 19, wherein the interface is a rail including a neckportion connected to the body and a lip portion connected to the neckportion, the lip portion having a first dimension greater than a seconddimension of the neck portion, and the outer wall having a thirddimension greater than the first dimension, the first, second, and thirddimensions extending between the top and bottom surfaces, and the neckportion separating the lip portion from the body at a first railsegment.
 21. The spacer of claim 19, wherein the plurality of teethcontact one another to completely cover a continuous portion of the atleast one of the top and bottom surfaces.